This invention relates to Loran Navigation Systems.
The present Loran C Navigation System provides a master transmitter and beacon and at least two secondary transmitters and beacons, also called slave beacons, as a complete chain identified by the repetition interval (GRI) of groups of radio frequency (RF) pulses from the beacons. All three beacons in a given chain operate at the same (GRI). The beacon pulses are accurately timed and phase coded for identification. Both the master and slave pulses are propagated as ground waves and as sky waves and all these signals as well as noise are detected by a Loran receiver antenna. The general purpose of the Loran Reciever is to measure the times of arrival of the two slave groups relative to the time of arrival of the master group and produce time differences, sometimes called TD1 and TD2 that identify hyperbolic coordinates on a map that intersect at the receiving antenna. Clearly, the more accurate TD1 and TD2 are computed, the more precise will be the determination of the position of the receiver on the map. Also, it is an advantage that the received signals be acquired rapidly and the measurement of of TD1 and TD2 be done quickly, particularly when the craft carrying the receiver is moving at high speed.